1. Field of the Invention
The present invention relates to a light-emitting apparatus comprising a light-emitting device, which emits fluorescent light or phosphorescent light upon application of an electric field thereto, including a pair of electrodes and an electroluminescent layer that is sandwiched between the pair of electrodes, and to a method of fabricating the light-emitting apparatus. Particularly, the present invention relates to technique for preventing moisture or oxygen from penetrating into the light-emitting device formed on a substrate by using a film containing fluoroplastics. In this specification, the term light-emitting apparatus includes an image display apparatus, a light-emitting device, or a light source (including a lighting system). Also, the following modules are included in the light-emitting apparatus: a module obtained by attaching a connector such as an FPC (flexible printed circuit), a TAB (tape automated bonding) tape, or a TCP (tape carrier package) to a light-emitting device; a module obtained by providing a printed wiring board with a tip of a TAB tape or a TCP; and a module obtained by mounting directly an IC (integrated circuit) to a light-emitting device by the COG (chip on glass) system.
2. Description of the Related Art
A light-emitting device, in which a material characterized by their thinness and light weight, fast response, and direct current low voltage driving is used as an illuminant, is expected to be applied to next-generation flat panel displays. Particularly, a light-emitting apparatus in which light-emitting devices are arranged in matrix are considered to be superior to the conventional liquid crystal display devices for their wide viewing angle and excellent visibility.
The luminescent mechanism of light-emitting device is as follows: voltage is applied to a pair of electrodes that sandwich an electroluminescent layer, and electrons injected from a cathode and holes injected from an anode are re-combined at the luminescent center of the electroluminescent layer to form molecular excitons, and then the molecular excitons return to the base state while releasing energy, consequently, luminescence is generated in the electroluminescent layer. Known excitation states are singlet excitation and triplet excitation, and it is considered that luminescence can be generated by either excitation states.
However, a light-emitting apparatus has a problem in the fabrication process, the problem is different from that of another display apparatuses such as a liquid crystal display apparatus, or the like.
It is known that a light-emitting device is deteriorated by moisture. Specifically, due to moisture, exfoliation between an electroluminescent layer and a electrode, deterioration of a material for forming an electroluminescent layer, generation of non light emitting portion referred to as a dark spot, or shrinkage of a light emitting portion resulting to inferior luminescence are seen in the light-emitting device. Such deterioration of the light-emitting device causes decreasing reliability of a light-emitting device in a long-time-driving.
The technique is known for solving the above described problems that Teflon®AF (a product by DuPont Corp.), polymer of Teflon® is formed by vapor deposition to seal a light-emitting device (for example, Reference 1: Patent Publication No. 2,597,047). Although the resulted film is effective for protecting the device from moisture or gas such as oxygen or the like, the film has some problems due to its peculiarities such that another film cannot be stacked on the resulted film. Consequently, the film cannot be patterned and can be formed exclusively on the surface of the light-emitting device.
On the contrary, the technique of forming a water-shedding film that is superior in abrasion-resistance by forming a mixed film of metallic oxides and fluoroplastics (for example, Reference 2: Unexamined Patent Publication No. 6-306591). The film has a merit of having advantages of both metallic oxides and fluoroplastics, on the other hand, the film has a demerit of having insufficient advantages in comparison with a single film.
As another solution, it is known that the technique of covering the external surface of the device by a dampproof film (for example, Reference 3: Unexamined Patent Publication No. 5-101884), or pasting an airtight case to a substrate for encapsulating a light-emitting device into an airtight space that is cutoff from the outside (sealing technique) (for example, Reference 4: Unexamined Patent Publication No. 5-36475 and Unexamined Patent Publication No. 5-89959). However, in this case, there is also problem of increasing the number of processes such as covering by a dampproof film, or pasting an airtight case a substrate, and there is a threat of further deterioration of a light-emitting device due to penetration of moisture or gas such as oxygen or the like thereinto during these processes.
Therefore attention is paid to how to give easily a light-emitting device a function of being protected against moisture or gas such as oxygen or the like without increasing the complicated processes as described above.